Gas exchange

Gas exchange?

The exchange of oxygen and carbon dioxide to and from the blood at the alveoli and respiratory tissue 

What is the role of diffusion in gas exchange?

Gas exchange is facilitated by diffusion allowing air to move across surfaces

Why do large organisms require large surface areas for gas exchange?

Diffusion is slow and organisms need large surface areas to make it more rapid

What are examples of ventilation systems?

• Insects trachea - Tubes from the exoskeleton used for gas exchange

• Fish gills - Remove co2 to water and extract o2

• Internal ventilation systems - The lungs

What are the properties of gas exchange surfaces?

• Permeability - O2 and CO2 can diffuse freely 

• Large surface area - Large total surface area in relation to volume of organism

• Moist - Covered in film of moisture so gasses can dissolve

• Thin tissue layer - The gasses must diffuse a short distance 

Why do concentration gradients needed to be maintained?

Diffusion evens out concentration gradients creating an equilibrium which ends gas exchange

How does cell respiration maintain the concentration gradient?

Oxygen is continuously used and carbon dioxide is continuously produced maintaining concentrations in organisms, O2 low on inside high on outside, CO2 High on inside low on outside

At a tissue level how is a concentration gradient maintained?

Blood flows through the circulatory capillaries constantly keeping a concentration between blood and tissue 

At a organ level how is concentration gradient maintained?

Ventilation moves air/ water actively through the lungs or gas over the respiratory surface maintaining a difference between air in the lungs and blood in the capillaries

The respiratory system?

A network of organs and tissues that enable exchange between the body and the enviroement

What are the locations of gas exchange in humans?

• The upper respiratory tract - nose, mouth, pharynx, larynx

• The lower respiratory tract - Trachea, bronchi, bronchioles

• Lungs - Pair of spongy organs that exchange gases between the blood and air

• Muscles - Diaphragm and intercostals that contract and relax to facilitate breathing

What structure of the lungs make it adapted for maximum gas exchange?

• Alveoli sacs being thin and having large surface areas for greater diffusion

• Surfactant creating moisture that reduced tension and prevent alveoli from sticking together 

• Capillary being thin enough to maintain the concentration of gasses and reduced the distance of diffusion 

• The lower respiratory tract having branching tubes to move air to and from the lung providing ventilation air ways

Ventilation?

The process of actively making air or water move over the respiratory surface

Inspiration?

The volume of the chest cavity increasing and decreasing the pressure in the lungs drawing air from the atmosphere

Expiration?

The volume of the chest cavity decreasing causing the pressure inside the lungs to increase

Outline the process of inspiration?

The diaphragm contracts, moving down, pushing the abdomen out, relaxing it, while the external intercostal muscles pull the rib cage up and out as the internal intercostal muscles relax, increasing volume and decreasing the pressure, allowing air to move from high to low pressure .

Outline the process of expiration?

The diaphragm relaxes into a dome shape while the abdomen contracts pushing the organs upwards, While the external intercostals relax and the internal intercostals contract pulling the rib cage in and down causing the volume to decrease and pressure increases in the lungs moving air pressure in the lungs to lower concentration outside the body

Ventilation rate?

The number of inspiration and expiration cycles per minute

Tidal volume?

The volume of fresh air inhaled or the volume of air exhaled within each ventilation

Inspiratory reserve volume?

The amount of air a person can inhale after normal tidal inhalation 

Expiratory reserve volume?

The amount of air a person can exhale forcefully after normal tidal exhalation

How can one measure tidal volume,vital capactity and insipatory and expiratory reserve volume?

• Spirometer

• Water displacement - Filling a container with water inverting it and blowing into a tube connected to the container displacing water